Many of the countries where people drive on the left are islands or continents: Britain, Ireland, Australia, New Zealand, and Japan, for example. But many left-driving countries share a land border with right-driving neighbours: Pakistan, India, Thailand, Namibia, Kenya, Guyana, and Suriname, for example. And this raises an interesting question: how do you switch sides at the border?

The boring answer, which is used in most of the world, is that you have a set of traffic lights and let cars and trucks switch over one direction at a time. The more interesting answer, of course, is to build a funky curly road that swaps cars around without stops. The picture above is a photo of the Lótus Bridge, which swaps traffic between mainland China (drive on the right) and Macao (drive on the left) without interrupting the flow of the highway.

Then there’s the service tunnel of the Channel Tunnel between Britain and France. It’s a two-lane tunnel for service vehicles, and I’ve been trying to find out which side those vehicles drive on. The English Wikipedia says that it’s left-side driving the whole way through, but most of the photos I can find shows service vehicles driving on the right. If anyone knows for sure, please let me know!